I'm wondering about moving the functionality of the 'configure extensions' dialog into the main configuration dialog.  As I don't know the history here, I'm wondering why it was made separate.

My proposal would be to add an 'Extensions' tab in the main config dialog. Along the left would be a listbox holding the names of each extension. Along the right would be options for the extension selected in the listbox (done pretty much the same as now). Selecting a different extension from the list would swap in the appropriate set of options.

This would have the additional advantage of doing away with the stacked tabs.